Method of making electric cables



Oct- 22, 1940. A. ARUTUNOFF 9F MAKING ELECTRIC CABLES METHOD Filed July10, 1937 .Z/E UP fie/m 1s zileurw/oFr.

Patented Oct. 22, 1940 UNITED STATES PATENT OFFICE Armais Arutunoff,Bartlesville, Okla", assignor to Reda Pump Company, Bartlesville, Okla,a corporation of Delaware Application July 10, 1937, Serial No. 152,984

3 Claims.

This invention relates to electric cables and more particularly to anovel method for making a multi-strand, multi-conductor cable, theconstructional features of which are claimed in my copendingapplication, Serial No. 152,983.

Many uses have now arisen in a wide variety of industries wherein it isimperative that the over all cross-sectional area of an electric cablebe reduced to a minimum. This is particularly true in the oil wellindustry where electric energy must be supplied to a submerged motoroften disposed many thousands of feet down within a deep well casing.Since the electric motor is often disposed below the pumping unit towhich it is operatively connected, and since a well casing rarelyexceeds a diameter of six or eight inches, it is apparent that thesmaller the diameter of the cable which conducts electric energy to themotor, the more desirable it is for use under these circumstances.

It is an object of this invention to provide a novel method of making acable suitable for use under conditions such as those indicated above.

Another object of this invention is to provide a novel method for makinga cable which is economical to manufacture and which is rugged andreliable in use.

It is a further object of this invention to provide a novel method ofmaking a cable which includes a central conductor and a plurality ofperipheral conductors twisted thereabout, there being a layer ofinsulating material between the central conductor and the peripheralconductors and between adjacent peripheral conductors.

It is a still further object of this invention to provide a novel methodof making a concentric conductor electric cable which includessimultaneously winding a plurality of peripheral conductors andinterposing or forming strips of insulating material about theinsulating jacket of a central conductor.

Another and further object of this invention is to provide a novelmethod of making a multiconductor electric cable, the cross-sectionalarea of each of said conductors being such that the electricalresistance of each conductor per unit length of cable is substantiallythe same under operating conditions.

' The novel features which I believe to be characteristic of myinvention are set forth with particularity in the appended claims. Myinvention itself, however, both as to its organization, manner ofconstruction, and method of operation, together with further objects andadvantages thereof, may best be understood by reference to the followingdescription taken in connection with the accompanying drawing in which:

Figure 1 shows an electric cable with the vari ous elements thereofbroken away successively along the length;

Figure 2 is a cross-sectional view of one form of a cable wherein theinsulating strip between adjacent peripheral conductors have been woundon the jacket of the central conductor simultaneously with the windingof the peripheral conductor;

Figure 3 is a cross-sectional view of another form of a three conductorcable, the insulating ribs between adjacent peripheral conductors beingintegral with the insulating jacket about the central conductor;

Figure 4 is a cross-sectional View of a preferred form of my cablewherein the insulating ribs between adjacent peripheral conductors havebeen formed from the yielding or semi-cured jacket 2 of centralconductor as a result of pressure of peripheral conductors on saidjacket.

Figure 5 is a cross-sectional view of a four conductor cable similar inconstruction to Figure 4; and

Figure 6 is a diagrammatic view illustrating one of the principal usesfor a cable such as that illustrated in Figures 1 to 5 and moreparticularly Figure 6 illustrates an oil well having a submersible motorand pump unit disposed therein and an electric cable extending down tosaid motor past the pump.

In Figure l, a multi-strand multi-conductor electric cable is shownwhich includes in general a central conductor ID, a layer of insulatingmaterial H disposed about the central conductor 10, peripheralconductors I2 and I 3 spirally wound about jacket ll, an outer jacket ofinsulating material l4 and an armored sheath IS. The central conductor10 is preferably formed of a plurality of tinned copper strands, thestrand interstices preferably being completely filled with a rubbercompound.

Peripheral conductors l2 and 13 also comprise a plurality of strands butinstead of being bunched together as the individual strands of thecentral conductor I0 are, the strands of the peripheral conductors l2and I3 are spirally wound flat against the outer surface of insulatingjacket I I.

Now one of the principal features of the present invention is the mannerin which the peripheral conductors l2 and 13 are assembled on the jacketH and the manner in which these conductors are insulated from eachother. One

embodiment of the present invention is illustrated in Figure 2 whichshows two insulating strips i6 and I1 which are wound about theinsulating jacket ll between conductors l2 and i3. Insulating strips l6and ii are preferably of reinforced construction as for example withfabric or thread to strengthen the cable as a whole.

Due to the fact and i3 are twisted about the central conductor Ill it isat once apparent that these peripheral conductors i2 and II are greaterin length than the central conductor. Therefore if the crosssectionalarea of the peripheral conductor were the same as the cross-sectionalarea of the central conductor the resistance of the peripheral conductorper unit length of cable would be greater than that of the centralconductor per unit length of cable. Due to the fact that cable such asthat illustrated in Figure 2 is designed primarily to transmit threephase alternating current electric energy, such a. difference in theresistance of the conductors per unit -of length would cause anundesirable unbalance of electrical characteristics between the phases.It is therefore important that the electrical resistance per unit lengthof cable be approximately the same under full load operating conditions.

It will also be appreciated that since central conductor I0 is furtherfrom the surface of the cable than are conductors l2 and I3 compensationmust be made for the thermal increase of resistance of the centralconductor due to a higher temperature thereof under full load operatingconditions. On account of the central location of the central conductorwithin the cable, heat created th ein can only be dissipated through thevery t ck insulation of the central conductor and the other conductors.It has been found in practice that under full load operating conditionsin certain instances the central conductor will be operating at atemperature requiring an allowance for increased resistivity of 9 to 13percent. It is important therefore, that the effective cross-sectionalarea of the central conductor Ill be such with respect to thecrosssectional area of the peripheral conductors l2 and 13 that theresistance of each conductor per unit length of cable be substantiallythe same under full load operating conditions.

The method and manner in which the cable illustrated in Figure 2 is madewill now be described. A central conductor II is formed composed of a;plurality of strands, seven being shown in the drawing and theinterstices between the strands are completely filled with a suitableinsulating compound such for example as a rubber compound. A jacket llof insulating material is then formed about the central conductor Ill.Peripheral conductors l2 and I3 each formed of a plurality of strands,seven being shown in each conductor in the drawing, are then spirallywound about insulating jacket ll. Preferably simultaneously with windingof peripheral conductors l2 and i3 r I orced insulating strips l6 and Hare wound thereon between conductors l2 and I3. Although reinforcedinsulating strips l6 and I! are preferably wound simultaneously onjacket II with peripheral conductors l2 and I3, it will be apparent tothose skilled in the art that insulating strips I6 and I! may be woundthereon either before or after the winding of conductors l2 and ISwithout departing from the spirit-and scope of the present invention.

the peripheral conductors l2 After peripheral conductors I2 and I3 andinsulating strips i8 and I! have been wound on insulating jacket ll ofcentral conductor it, an

outer Jacket ll of suitable insulating material is formed thereabout.Over the outer jacket ll the usual layer of tape and braid is formed asis indicated at it in Figure 2. The tape is preferably oilproofvarnished cambric and the braidis preferably woven single braid whichhas been thoroughly impregnated with an oilproof lacquer.

An armored sheath I5 is finally formed about the cable which ispreferably of the interlocking galvanized steel strip type.

In Figure 3 of the drawing a different embodiment of the invention isillustrated. More particularly a jacket IQ of insulating material isformed about the central conductor II having integral ribs 20 and 2!formed thereon with a plurality of groovelike indentations 31 therebe-'tween. The ribs 20 and 2| form suitable insulating partitions betweenperipheral conductors i2 and I 3. The construction of the cable shown inFigure 3 is otherwise similar to that shown in Figure 2, and althoughintegral ribs 20 and 2! and indentations 31 may be preformed in a spiralabout the main body portion of insulating jacket l9, it is preferablefrom a manufacturing standpoint and from an economical standpoint toform the insulating jacket II with ribs 20 and 2| and indentations 31extending longitudinally thereof. 1

The central conductor l0 and its jacket II is then twisted during theapplication of the peripheral conductors l2 and I3 thereto, theindividual strands of conductors l2 and I3 being disposed inindentations 31, such that'the longitudinally disposed ribs 2. and 2|are twisted into spirals between which the peripheral conductors l2 andi3 are wound. Although it is my cable wherein a three conductor 'cableis. made up of a central multi-strand conductor I I and two peripheralconductors l2 and I3, but wherein the jacket IQ of the central conductoris left in semi-cured condition; that is, jacket I9 is left soft enoughto permit, under pressure of cabling, the sinking of peripheralconductors l2 and I3 therein thus forming ribs 20 and 2i out of anordinary jacket of circular cross-sectional configuration such as H ofFigure 2.

After the peripheral conductors l2 and i3 have been wound an outerjacket ll of suitable insulating material is.formed thereabout and thewhole assembly is vulcanized together.

It must be noted that irrespective of which of the three constructionsis employed, it is important that the ribs, partitions or fillers bece-.

mented, bonded or welded to the adjacent jackets, rather than merely tocome in contact therewith in order to accomplish an electrical barrierof .high dielectric strength. I

For the abovereason the construction of Figure 4, employing semi-curedrubber or rubber-like material, has advantages over constructions ofFigures 2 and 3 in. that semi-cured materials bond together easier andhave the further advantage of being manufacturabl'e on ordinary cablingmachines whereas the constructions of Figures 2 and 3 usually requirespecial machines.

In the commercial manufacture of the cable illustrated in Figure 4, ithas been found highly desirable to build up and form the cable in onecontinuous process. Specifically the jacket I! of the central conductorIll is formed about the multi-strand central conductor in and theresulting unit is then passed through a cabling machine where theperipheral conductors l2 and H are wound on the jacket l9 under apressure sufllcient to embed them' therein. The cable is then passedthrough a jacketing, machine which applies thereto an outer jacket I. Onleaving the jacketing machine the cable is leaded and then wound on asuitable reel or the like where the jackets I9 and M are vulcanized orotherwise suitably bonded together. The cable thus formed is economicalto manufacture and extremely rugged and reliable in use.

Figure 5 shows a still further embodiment of the present inventionwherein a four conductor cable is made up of a central multi-strandconductor l0 and three multistrand peripheral conductors 22, 23 and 24.The insulating jacket about the central conductor Ill forms in thisinstance three insulating ribs 28, 21 and 28 which serve to space andinsulate peripheral conductors 22, 23 and 24 from each other. The fourconductor cable of Figure 5 is formed in substantially the same manneras that described in connection with Figure 4.

In Figure 6 of the drawing I have illustrated schematically an instancewherein a cable of the type illustrated in Figure 2, Figure 3, Figure 4,or Figure 5 may be advantageously employed. A submersible motor and pumpunit including a motor 28 and a pump are shown suspended in a deep well30 from the surface of the ground ll The inlet of the pump is indicatedat 32 and the discharge conduit is indicated at 33. Extending from areel 84 is a cable 35 such as that described above which passes downinto the well past the pump 29 to the motor 2! thereby to conductelectric energy from the electric supply panel I! to the motor.

5 Although the cable has been described as being units in oil wells itwill be appreciated that a cable constructed in accordance with theteachings of the present invention has a wide variety of uses in manyother industries.

While I have shown particular embodiments of my invention, it will ofcourse be understood that I do not wish to be limited thereto as manymodifications may be made, and I therefore contemplate by the appendedclaims to cover all such modifications as fall within the true spiritand scope of my invention.

I claim as my invention:

1. The method of making concentric electric cable for power transmissionwhich includes covering a conductor with a layer of semi-curedinsulating material, spirally winding at least two bare multi-strandperipheral conductors thereon under sufficient pressure to embed thestrands of said peripheral conductors in said insulating material,thereby forming partitions or ribs between said peripheral conductors,forming .an outer jacket of suitable insulating material embracing saidperipheral conductors and said ribs and bonding said outer jacket tosaid ribs by vulcanizing the whole assembly.

2. The method of making concentric cable for electrical powertransmission which includes covering a multi-strand central conductorwith a jacket of yielding insulating material, twisting at least twomulti-strand peripheral bare conductors having relatively smallcross-sectional area with respect to said central conductor about saidjacket and embedding the strands of said peripheral conductors in saidjacket of yielding material in such manner as to form insulating ribsbetween said peripheral conductors, and applying an outer jacketthereabouts which bonds itself to the exposed parts of said centraljacket.

3. The method of making a concentric cable for electrical powertransmission which includes covering a central conductor with a jacketof yielding material, twisting at least two bare multi-strand peripheralconductors around said jacket under a pressure sufllclently high toembed said peripheral conductors in their respective spiral position onsaid jacket.

ARMAIS ARUTUNOFF.

